Anaerobic radiometric detection of facultative Gram-positive cocci in blood.

Radiometric detection of facultative gram-positive cocci, particularly streptococci, has been reported to be suboptimal. A recently marketed anaerobic Bactec bottle (7C) with purportedly improved capability to detect facultative gram-positive cocci in blood was compared with the previously available bottle in a study of simulated bacteremia. The Bactec system detected all beta-hemolytic streptococci and enterococci tested. Detection of alpha-hemolytic streptococci was improved in general. However, detection of Streptococcus mutans, Streptococcus bovis and Streptococcus pneumoniae remained suboptimal under anaerobic conditions. A metabolic index unit threshold for positivity of 15 is recommended when employing the anaerobic Bactec bottle.